Why you don,t use the stock nylon coated aluminum gears on a high performance engine build










read this
http://forum.grumpysperformance.com/...9&p=7625#p7625

BTW, if your still not convinced, think about WHERE all those little pieces of nylon go and what they do,if your clueless...they tend to block or restrict the oil flow into the oil pump pick-up and get ground up and forced into the oil passages by the pump gears


The CLOYES true roller style is vastly superior




how come its 180 degs out of phase?
I get this question all the time, well here’s something I see lots of guys don’t understand, ONCE YOUVE INSTALLED A CAM WITH THE TIMEING MARKS YOU MUST ROTATE THE CRANK 360 DEGRESS BEFORE DROPPING IN THE DISTRIBUTOR, while its true that if the, timing marks are positioned so the crank is at 12 o,clock and the cam gear is at 6 o,clock that the cam lobes will be in the position that fires #6 cylinder that HAS NO EFFECT AT ALL (on finding TDC,) for aligning the degree wheel with TDC,or THE timing tab pointer, for degreeing in the cam, the piston passes thru TDC TWICE in every firing cycle once on the firing/power stroke and once on the exhaust stroke, the cam rotates at exactly 1/2 the speed of the crank so to make it easy to line up the marks they install it with the marks at the closest point 6/12 for easy indexing, rotate the engine 360 degrees to the #1 TDC power stroke and the crank gear will still be at 12 oclock 12/12 but the cam will be at 12 o,clock also, rotate another 360 degrees and your back where you started. its simply easier to index the cam at the point where the index marks align closely. look at how the cam lobes themselves open the valves when the cam is just installed the #1 cylinder valves are slightly open and the #6 are closed per "Lunati" ‘’YES YOU ARE RIGHT - WHEN CRANK IS AT TWELVE AND CAM IS AT SIX THEN #6 CYL IS FIRING AFTER YOU LINE UP YOUR MARKS AND INSTALL GEAR THEN ROTATE YOUR CRANK ONE REVOLUTION AND THEN DROP THE DIST. IN - AT THAT POINT

 

Yikes! That's not so good, is it? Makes you wonder why the factory every used them at all. Always seemed like a lot of work to me to bond a set of nylon teeth onto a metal gear in the first place- like why did they ever bother to do it anyway? I agree- if it's a critical engine component like a timing set it should be made of metal. And a perfectly good all-steel timing chain set can be had for so cheap it makes you wonder why anyone would ever consider using anything else.

 

The nylon gear is used by the factory for longivity to reduce the wear on the timing chain.

 

Who is dumb enough to re-use the factory chain and gears on a buildup?

 

Ditto! Nobody I know of. If your concerned with performance, your not worried about getting 100k miles out of a performance build up!

 

Would you believe noise? GM used a steel gear up to 1969. They wanted to cut the idling noise when the car was in the showroom. Back then the life expectancy of a car was 100,000 miles and the nylon gear would last that long so they went with the quiet idle.

 

I remember my dad telling me about the brand new 69 GTO he had years ago. That crappy, nylon coated timing gear fell apart with only about 30K on the motor! Of course he did what any sensible gearhead would do, and replaced it with a steel, double roller chain. Good point on the timing marks issue too. I ended up getting several distributors 180 degrees off in my youth before I figured out it's not at TDC #1 unless the marks are at 12/12. It's definitely easier to line up the marks at 6/12 though.

 

I kniow this is an old thread but I would like to present my evidence of GM's stupid idea to use nylon.